Band sealer for cigarette or filter maker

ABSTRACT

A BAND SEALER FOR SEALING THE MARGINS OF CIGARETTE WRAPPER PAPER OR CIGARETTE FILTERS USING A THIN STRIP HEATER ELEMENT. THE SEALER COMPRISES A PLURALITY OF NON-CONDUCTING COAXIALLY-INTERCONNECTED SEALER BLADES WITH A WEIGHTED HOUSING FOR HOLDING THE BLADES AGAINST THE WRAPPERS TO BE SEALED, A SMALL AND NARROW METAL HEATING ELEMENT CONNECTED TO AND EXTENDING ACROSS THE BASE OF THE BLADES ENGAGING THE WRAPPERS AND RESPONSIVE TO RAPID CHANGES IN TEMPERATURE, A SPRING URGING THE BLADES APART FOR HOLDING THE HEATING ELEMENT TAUT SO THAT IT WILL APPLY EVEN HEAT TO THE WRAPPERS, AND A CONTROL CIRUIT INCLUDING THERMOCOUPLE SENSORS AND AN OPERATIONAL AMPLIFIER WHICH INCREASES THE STRENGTH OF THE SIGNALS SENT BY THE THERMOCOUPLE SENSORS FOR MAINTAINING THE HEATING ELEMENT AT A PREDETERMINED TEMPERATURE.

' April 20, .1971 c, 5, Q T'H ETAL 3,575,766 BAND SEALER FOR CIGARETTE 0R FILTER MAKER HEATER ELEMENT PHA E CONTROL CIRCUIT Filed 0012.459, 1968 a. 42 I I OPERATIONAL AMPUFIER THERMO- COUPLE INVENTOR. Com/v5. flfcflemue B MAX /l 5,4/15? ATTOR/UE) United States Patent 3,575,766 BAND SEALER FOR CIGARETTE R FILTER MAKER Colin Shaw McArthur, Winston-Salem, and Max Norris Baker, Rural Hall, N.C., assignors to R. J. Reynolds Tobacco Company, Winston-Salem, N.C.

Filed Oct. 29, 1968, Ser. No. 771,399 Int. Cl. B32b 31/20 US. Cl. 156-359 4 Claims ABSTRACT OF THE DISCLOSURE A band sealer for sealing the margins of cigarette wrapper paper or cigarette filters using a thin strip heater element. The sealer comprises a plurality of non-conducting coaxially-interconnected sealer blades with a weighted housing for holding the blades against the wrappers to be sealed, a small and narrow metal heating element connected to and extending across the base of the blades engaging the wrappers and responsive to rapid changes in temperature, a spring urging the blades apart for holding the heating element taut so that it will apply even heat to the wrappers, and a control circuit including thermocouple sensors and an operational amplifier which increases the strength of the signals sent by the thermocouple sensors for maintaining the heating element at a predetermined temperature.

BACKGROUND OF THE INVENTION The present invention relates to the cigarette making art and more particularly to an improved band sealer for sealing the margins of cigarette wrapper or cigarette filters.

One of the most critical components in an apparatus for manufacturing cigarettes is the band sealer, which heat seals the margins of the cigarette paper together to form a neat and trim rod after the paper has been filled with tobacco and paste. has been applied to one margin of the paper. Such devices have been in use, of course, for many years and have more recently been employed in preparing filters for use with cigarettes.

The existing band sealers have generally utilized quite massive heating sections and sealer blades to apply heat to the previously pasted and folded margins of the cigarette paper. The use of large sealer blades as the heating element results in rather slow response to changes in temperature when the controls are applied, such as upon commencing or terminating the manufacturing operation. Moreover, because of the large mass of the heating element, several times the input power that is actually needed for sealing is required. This latter characteristic produces the consequence of considerable overshoot in temperature when the machine is being controlled or when it is temporarily inactive. Thus, a large quantity of cigarettes or filters may be wasted when the heating element overheats, burning the wrapper paper, or conversely fails to provide enough heat to properly seal the paper. A further disadvantage of the present method of sealing cigarette paper wrappers is that in time the tolerance between the heat source and sink gradually increases causing poor heat transfer to the heating element and a short heating element life.

The present invention is directed toward improvements in controlling the heat transfer to the heater element and the cigarette wrapper in a band sealer.

SUMMARY OF THE INVENTION The improved heat transfer control of the present invention is accomplished by employing a plurality of smaller interconnected sealer blades and using a small and narrow thin strip heating element attached to the Patented Apr. 20, 1971 sealer blades and held taut against their lower surfaces by a spring within the sealer blades urging them apart. The power supply utilizes thermocouple sensors in combination with an operational amplifier to provide more rapid response in the heating element to changes in temperature.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of the band sealer of the. present invention showing its relation to the surrounding apparatus in a cigarette-making machine;

FIG. 2 is an enlarged perspective view of the band sealer of the present invention with parts broken away to show inner structural details;

FIG. 3 is a sectional view taken on line 33 in FIG. 1 but showing the band sealer in its operational position in the surrounding apparatus; and

FIG. 4 is a block diagram of the heater element controls of the present invention.

DETAILED DESCRIPTION The band sealer of the instant invention is shown in FIG. 1, designated generally by the numeral 10. The heated sealer 14) is operationally positioned in a recess 24 in a folder block 20 to engage the surface of a cigarette wrapper 11 after folding by the block 20. In accordance with manufacturing practices known in the art, the cigarette paper wrapper 11 is filled with tobacco 13 with one margin 12 of the wrapper held higher than the other margin 14. The filled paper 11 is passed rapidly between an idler 17 and a paster wheel 16 which applies a sealing paste to the inner edge of the higher margin 12. The paper 11 is then formed into a long, narrow cylinder as it moves through a shaped channel 18 on the folder block 20, which is attached to the bed of the machine 22. The band sealer 10', contained in the recess 24 in the folder block 20 at the end of the shaped channel 18, applies heat to the pasted margin so that the filled cigarette wrapper 11 will be nearly instantaneously heatsealed as it passes out of the shaped channel 18. A sensing head 26 at the downstream end of the folder block 20 determines whether the completed cigarette rods are of the proper diameter and causes any necessary adjustments to be made such as through fluid amplifier controls (not shown), which work a lever 28 and a control rod 30 to raise or lower the folder block 20 repositioning the shaped channel 18.

The particular construction of the band sealer 10-, is most clearly illustrated in FIG. 2. Instead of using one sealer blade to transfer heat to the cigarette wrapper seam as in the prior art, two or more smaller blades 32 with cooperating mortised ends shaped to fit coaxially, are employed. These blades 32 are fashioned of a heat-resistant, nonconducting material and are much smaller in size than the massive blades used in existing devices of the kind already mentioned. To compensate for their lack of weight, the blades 32 support a saddle weight 34 which may be constructed of any suitable material that will provide the necessary weight to hold the blades 32 against the passing cigarette wrapper 11.

The actual heating element is a thin, narrow metal strip 36 which conducts the heating current. The metal strip 36 is fastened at its opposite ends to suitable leads 33 of an electrical power supply (not shown) and to the upper surfaces of the blades 32 at their outer ends. The intermediate portion of the strip 36 extends through grooves 35 in the blade ends and along the lower edges of the blades 32 engaging the outer surface of the pasted margin 12 of the passing wrapper 11. The metal strip 36 serves to provide localized and concentrated heat for sealing the pasted wrappers 11. This strip may be of a durable metal, such as Nichrome or stainless steel, and shouldbe of small dimensions and mass, e.g., about A" wide by .030" thick. Of course, the dimensions and materials may be varied to suit the particular usage, but, it has been found that the smaller the mass of the heating element, the more sensitive it is to the controls and the less likely it is to burn the passing wrapper. On the other hand, too small a heating element may fail to seal the wrapper, as it moves through the sealer at a speed of several thousand feet per minute. The exact size of the strip used will depend on the dimensions of the blades and the processing speed of the entire operation.

As tautness of the heating element 36 is important to maintain uniform heat along the wrapper, a compression spring 38, acting in mating central recesses in the blades 32, is provided to urge the blades apart and keep the metal strip 36 in tension. The metal strip 36 is thereby prevented from scorching portions of the Wrapper while failing to seal other portions.

Heat sensing elements, such as thermocouple sensors 40, are positioned in recesses in the blades 32, near both ends of the strip 36, and are in contact with the upper surface of the metal strip 36. These thermocouple sensors 40 are used to sense the temperature of the strip 36 and provide an indicative signal to a control circuit which determines the correct power input to maintain the pre-set temperature. As the strip 36 and the thermocouple sensors 40 are both small in mass, the changes in heat transfer required may take place rapidly, thus providing good control over the amount of heat eventually transferred to the cigarette wrappers 11. The more rapid the operation of the controls, the fewer the cigarettes that will be wasted due to poor sealing. Thermocouple sensors are preferable to other heat sensing elements, such as thermistors, for the purpose of the present invention as they are more stable and rugged than thermistors.

The control circuit for operating and regulating the heating current to the strip 36 is shown generally in FIG. 4. Temperature indication signals from the thermocouple sensor 40 are sent to an operational amplifier 42, which amplifies the output level of the signals to an acceptable operating value. The amplifier 42 may be an integrated circuit, which increases the strength of the small D.C. potential of the thermocouple signal. The amplifier 42 operates a phase control circuit 441 which turns on A.C. power to the heater element 36. The phase control circuit 44 operates in such manner that power is supplied to the heater element 36 increasingly later in the half-cycle of the pulse wave as the temperature increases, thus resulting in less heat being transferred to the heater element 36. The phase control circuit 44 conversely turns on the heating element 36 earlier in each half-cycle when the temperature decreases.

It will be seen that an improved band sealer is provided of simple, lightweight construction and which requires less operating power and has improved heat transfer capabilities over the apparatus of the prior art.

What is claimed is:

1. A band sealer comprising: I

(a) means for transferring heat to the material to be sealed;

(b) means for holding said heat transfer means against the material to be sealed; and

(c) control means for maintaining the heat transferred to the material to be sealed at a predetermined level;

the improvement wherein said heat transfer means comprises:

(d) a thin strip of electrically conductive material attached to said holding means;

and said holding means comprises:

(e) a plurality of aligned non-conducting blades expansibly connected to each other with the end of the strip attached to different blades; and

(f) compression spring means urging said blades apart to maintain said strip in tension.

2. A band sealer as claimed in claim 1 wherein said holding means comprises a weighting means mounted on said blades.

3. A band sealer as claimed in claim '1 wherein said control means comprises:

(g) means for sensing the temperature of said strip and producing an indicative signal;

(h) an integrated circuit connected to said sensing means for amplifying said signal; and

(i) a phase control circuit connected between said integrated circuit and said strip for turning on A.C. power to said strip at different points in the half cycle of the pulse wave to accordingly vary a heating current to said strip inversely with respect to the magnitude of said signal.

4. A band sealer as claimed in claim 3 wherein said temperature sensing means comprises a thermocouple in contact with said strip.

References Cited UNITED STATES PATENTS 1,705,224 3/1929 Mouns 156-535 2,958,366 11/1960 Conti 156-378 3,015,600 1/1962 Cook 156515 3,106,630 10/1963 Klamp 156- 583 3,113,198 12/1963 Shinn 156-583 3,243,574 3/1966 Blythe et al 156583 3,266,968 8/1966 Von Gunten 156502 BENJAMIN A. BORCHELT, Primary Examiner I). A. BENT, Assistant Examiner US. Cl. X.R. 

